Mycoplasma genitalium

Mycoplasma genitalium (MG) is a bacterium that causes urogenital infections. It is increasingly recognized as a significant STI but is often missed because it is not included in standard STI panels at many clinics. MG is associated with urethritis in people with penises, and cervicitis and pelvic inflammatory disease in people with vaginas. Antibiotic resistance is a major and growing concern.

Mycoplasma genitalium spreads through vaginal and anal sex. Whether it spreads through oral sex is uncertain. Like many STIs, it can be transmitted even when no symptoms are present. MG infection may increase susceptibility to HIV and other STIs.

Most people with MG have no symptoms. When present:

• In people with penises: burning or pain when urinating, discharge from the urethra
• In people with vaginas: unusual vaginal discharge, pain during sex, pelvic pain
• Both: rectal discharge or discomfort (if anal sex)

Untreated MG can cause serious complications:

• Pelvic inflammatory disease (PID)
• Increased risk of ectopic pregnancy
• Potentially affects fertility
• Reactive arthritis (rare)

MG is diagnosed with a NAAT test (urine sample or genital/rectal swab). Key points:

• Not in routine panels at many clinics — ask specifically for MG testing
• Resistance testing is recommended before prescribing antibiotics (to determine which antibiotic will actually work)
• Some areas have point-of-care resistance tests; others require sending samples to a lab

If you have symptoms of urethritis or cervicitis and standard STI tests are negative, ask about MG.

MG is treated with antibiotics, but antibiotic resistance is a serious problem:

• Recommended approach: doxycycline for 7 days first, then azithromycin (if macrolide-sensitive) or moxifloxacin (if macrolide-resistant)
• Resistance-guided therapy is preferred: test for macrolide resistance first, then choose the appropriate second-step antibiotic
• A single dose of azithromycin alone is no longer recommended due to high resistance rates
• Treatment failure is increasingly common — follow-up testing to confirm cure is essential

Avoid sex until treatment is confirmed complete. Sexual partners should also be tested and treated.

Prevention steps:

• Condoms reduce transmission risk
• Get tested if you have symptoms of urethritis or cervicitis — ask specifically for MG if standard tests are negative
• Treat partners to prevent re-infection
• Avoid unnecessary antibiotic use — antibiotic overuse drives resistance

Awareness is key: MG is underdiagnosed because many people and providers don't know to test for it. If you have persistent genital symptoms with negative standard STI results, MG may be the cause.